• Title, Summary, Keyword: Floating slab

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Influence of Slab Length on behavior of Floating Slab Track by Rail-slab-isolator Longitudinal Interaction

  • Nguyen, Huan Ha;Jang, Seung Yup;Chung, Wonseok
    • International Journal of Railway
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    • v.5 no.4
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    • pp.163-166
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    • 2012
  • Many different types of floating slab track have been developed and installed around the world to reduce vibrations and noise originating in the surrounding environment. The main objective of this study is to examine the influence of slab length on behavior of floating slab track based on rail-slab-isolator interaction. The floating slab track is modeled by the connection between rail, slab, isolator, and slab mat in the transition zone. All elements were assembled in a simplified two-dimensional (2D) finite element model (FEM). The maximum length of FST is then investigated based on the maximum additional rail stress criterion as described in UIC 774-3R since no fully accepted design criteria for the slab length in FST systems currently exist.

Dynamic Behavior of Train and Track at Slab Joints of Floating Slab Track (플로팅 슬래브궤도 슬래브 연결부에서의 차량 및 궤도의 동적 거동)

  • Jang, Seung-Yup;Yang, Sin-Chu;Hwang, Sung-Ho;Ahn, Mi-Kyung;Choi, Won-Il
    • Proceedings of the KSR Conference
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    • pp.993-997
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    • 2011
  • Highlighted is significance of the floating slab track for mitigating vibrations induced by train, together with the recent trends towards speed-up of railways. In the design of the floating slab track, it is more beneficial to increase the slab length since a significant impact can be induced on the train and track at the discontinuous points between slabs with the finite slab length. However, if the slab length is too long, the tensile stress of slab concrete and the additional stress on rail due to the temperature change and shrinkage of concrete slab. Thus it is of great importance to relevantly determine the slab length. In this study, to understand these phenomena and establish the countermeasures, the dynamic behaviors of train and track at the inter-slab discontinuous points have been explored and the effect of dowel joints as one of countermeasures has been analytically investigated.

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Maximum Slab Length of Floating Slab Track (플로팅 슬래브 궤도의 최대길이)

  • Huan, Nguyen Ha;Jang, Seung-Yup;Chung, Won-Seok
    • Proceedings of the KSR Conference
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    • pp.173-180
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    • 2011
  • Recently, many railway stations are built under the railway line in urban area. The passage of railway vehicles generates mechanical vibrations of a wide range of frequency. Thus, it is required to place structural vibration isolation systems to reduce vibration and noise originating from surrounding environments. This study is to investigate the maximum floating slab length based on track/floating slab interaction analyses. Actions to be taken into account include temperature, braking/acceleration, bending of the deck, and creep/shrinkage. The additional rail stress has been chosen for the criterion for the maximum slab length. In addition, further analyses are performed to include the stopper which restrict the in-plane movement of the floating slab track. Several alternatives for stopper positions were thoroughly studied in this study.

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Static and Dynamic Behavior at Low-Frequency Range of Floating Slab Track Discretely Supported by Rubber Mounts in Real-Scale Laboratory Test (고무 마운트로 이산 지지되는 플로팅 슬래브 궤도의 실모형 실내 실험에서의 정적 및 저주파 대역 동적 거동)

  • Hwang, Sung Ho;Jang, Seung Yup;Kim, Eun;Park, Jin Chul
    • Journal of the Korean Society for Railway
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    • v.15 no.5
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    • pp.485-497
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    • 2012
  • Recently, with increasing social interests on noise and vibration induced by railway traffic, the application of floating slab track that can efficiently reduce the railway vibration is increasing. In this study, to more accurately understand the dynamic behavior of the floating slab track, a laboratory mock-up test has been performed, and the static and dynamic behaviors at frequency range near the system resonance frequency were explored. Based on the test results, the design of the floating slab track and the structural analysis model used in the design have been verified. The analytic and test results demonstrate that the dominant frequency of the floating slab track occurs at the frequencies between vertical rigid body mode natural frequency and bending mode natural frequency, and the dominant deformation mode is close to the bending mode. This suggests that in the design of the floating slab track, the bending rigidity of the slab and the boundary conditions at slab joints and slab ends should be taken into consideration. Also, the analytic results by the two-dimensional finite element analysis model using Kelvin-Voigt model, such as static and dynamic deflections and force transmissibility, are found in good agreement with the test results, and thus the model used in this study has shown the reliability suitable to be utilized in the design of the floating slab track.

Analysis of Behavior of Train and Track at Transition Zone between Floating Slab Track and Conventional Concrete Slab Track (플로팅 슬래브궤도와 일반 콘크리트궤도 접속부에서의 열차 및 궤도의 거동 분석)

  • Jang, Seung-Yup;Yang, Sin-Chu;Park, Man-Ho;Joh, Su-Ik
    • Proceedings of the KSR Conference
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    • pp.379-384
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    • 2009
  • It is of great importance to assure the running safety and ride comfort in designing the floating slab track for the mitigation of train-induced vibration. In this paper, for this, analyzed are the system requirements for the running safety and ride comfort, and then, the behavior of train and track at the transition zone between the floating slab track and the conventional concrete slab track according to several main design variables such as spring constant, damping coefficient, spacing and arrangement of isolators and slab length, using the dynamic analysis technique considering the train-track interaction. The results of numerical analysis demonstrate that the discontinuity of the support stiffness at the transition results in a drastic increase of the vertical vibration acceleration of the train body, wheel-rail interaction force, rail bending stress and uplift force. The increase becomes higher with the decrease of the spring constant of isolators and the increase of the isolator spacing, but the damping ratio does not significantly affect the behavior of train and track at the transition. Therefore, to assure the running safety and ride comfort, simultaneously increasing the effectiveness of vibration isolation, it is effective to minimize the relative vertical offset between the floating slab and the conventional track slab by adjusting the spring constant and spacing of isolators at the transition.

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Vibration Analysis of Station under Railway Lines with Floating Slab Track (플로팅 슬래브궤도를 적용한 선하역사 구조물 진동해석)

  • Jang, Seung-Yup;Cho, Ho-Hyun;Yang, Sin-Chu
    • Proceedings of the KSR Conference
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    • pp.1719-1724
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    • 2010
  • In the areas susceptible to vibration and noise induced by railway traffic such as downtown area and stations under railway lines, the vibration and the structure-borne noise can be solved by floating slab track system separating the entire track structure from its sub-structure using anti-vibration mat or springs. In other countries, the core technologies for vibration-proof design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the design technology of system and components are not yet developed, the foreign systems are being introduced without any adjustment. Thus, in this study, the vibration isolator has been developed and its performance are investigated by the dynamic analysis of a station structure under railways lines and the floating slab track system. For this purpose, the loads transferred from the vibration isolator of the floating slab track were evaluated by train running simulation considering vehicle-track interaction, and then the dynamic analysis of station structure subjected to these loads was performed. The dynamic analysis results show that the proposed floating slab track can reduce the vibration of structure by about 25dB compared with that in conventional ballast track without floating system.

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Evaluation of Vibration and Noise character on the Floating Slab Track (부유궤도의 진동$\cdot$소음 특성 평가)

  • Hun Young;Lee sang jin;Kim gi hun;Lee in se
    • Proceedings of the KSR Conference
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    • pp.343-348
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    • 2003
  • As one of countermeasures for vibration and noise source which come from train operation in subway system, the heavy-weighted tunnel structure and the low-vibration track design have been adopted. In recent the low-vibration concrete track have been constructed to enhance the maintenance effectiveness as well as the reduction of vibration. This paper is explaining and evaluating of the characteristics of vibration and its effects comparing to tile ballast track, concrete track, and full surface supported floating slab track installed on Express bus terminal in Seoul subway No. 7 line.

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Vibration Analysis Method for Railway Structure with Floating Slab (방진궤도가 부설된 역사의 진동해석 기법)

  • 양신추;김태욱;강윤석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.561-566
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    • 2003
  • In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under floating slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effects of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

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Strength Analysis of Joints in Floating Slab Track (플로팅 슬래브궤도 연결부의 강도 분석)

  • Kwon, Ku-Sung;Chung, Won-Seok;Jang, Seung-Yup
    • Proceedings of the KSR Conference
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    • pp.375-381
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    • 2011
  • The passage of railway vehicles generates mechanical vibrations and noises. This problem can be mitigated by the 'floating slab track' that isolating from infrastructures by installing vibration isolator in the concrete slab track. In the previous researches, adjacent floating slab tracks are connected by dowel bar system. It has been reported that many dowel bars with less diameter show better load transfer efficiency (LTE) compared to small number of dowel bars with larger diameter under the condition of the same dowel area. In this study, dowel system is further considered as a concrete anchorage system and the design strength of the dowel system was evaluated based on ACI code 318-08 Appendix D. The design strength of dowel system is then verified against failure load test of floating slab system.

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Analysis of Dynamic Behavior of Floating Slab Track Using a Nonlinear Viscoelastic Spring Model (비선형 점탄성 스프링 모델을 이용한 플로팅 슬래브 궤도의 동적 거동 해석)

  • Jang, Seung Yup;Park, Jin Chul;Hwang, Sung Ho;Kim, Eun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.11
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    • pp.1078-1088
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    • 2012
  • Recently, the vibration and structure-borne noise induced by passing trains are of great concerns, and the floating slab track is highlighted as one of most efficient alternatives to reduce the railway vibration. However, due to the non-linearity and viscosity of rubber spring used in the floating slab track, its dynamic behavior is very complex. In this study, therefore, to simulate the dynamic behavior of floating slab track with a better accuracy, a nonlinear viscoelastic rubber spring model that can be incorporated in commercial finite element analysis codes has been proposed. This model is composed of a combination of elastic spring element, friction element and viscous element, and termed the "generalized friction viscoelastic model(GFVM)". Also, in this study, the method to determine the model parameters of GFVM based on Berg's 5-parameter model was presented. The results of the finite element analysis with this rubber spring model exhibit very good correlation with the test results of a laboratory mock-up test, and the feasibility of GFVM has been verified.